Joint construction



Jan. 15, 1946;

M. WATTER JOINT CONSTRUCTION Filed June 28, 1943 10 Sheets-Sheet 1 AMI . j INVENTOR Q 5 Michael Waiterg ATTORNEY Jan.15,1946. M, ATTER 2,393,081"

JOINT CONSTRUCTION Filed June 28, .4 43 10 Sheets-Sheet 2 v v 16 w INVENTOR Michael Wat tar A TTORNE Y 46 FICn L- 10,1!15, 1946. v M. WATTER 2,393,031 JOINTCONSTRUCTION Filed June 2a, 1943 ;1.0 Sheets-Sheet s I N V EN TOR Michael Waiter ATTORNEY F1 (PRE-ASSEMBLY 0F FIC1.4-)

JOINT CONSTRUCTION Filed June 28, 1943 v 10 Sheets-Sheet 4 I INVENTOR Minhael Waiter.

B j F1015 A W- ATTORNEY Jan. 15, 1946.

M. WATTER JOINT CONSTRUCTION Filed June 28, 1943 10 Sheets-Sheet 5 nvwzzvroR Michael Wat her.

A TTORNE Y Jan. 15, 1946. M. WATTER JOINT cousmucwion 5* If M r H...|ililllillflk m m E 6 a M a v a m W o M W 1 T w t 38% u 30M mm on $0. m v

Filed'June 28 Jan. 15, 1946. j A 2,393081 JOINT coNsTRucTIoN 7 Filed June 28, 1943 1o Sheets- Sheet 7 FIGiQ (on FIG 1a) a I INVENTOR 9 Michaelwoicer ATTORNEY Jan. 15, 1946. v M. WATTER I 2,393,031

JOINT CONSTRUCTION Filed June 28,A943 1O Sheets-Sheet 8 IQEHEMHIUI INVENTOR Michael Wafier FT C12? (on FIG-7.7.) (on FIG/7.7.) M

' I I .ATTORNEY Jan. 15, 1946. M. WATTER JOINT CONSTRUCTION -F.i:ld June 28, 1943 10 Sheets-Sheet 10 R m m m F1632 Michael Whiter (PRE- ASSEM-BLY or- FIG-34) BY W ATTORNEY desirable for of large airfoils,

D rts, Viz an In airfoils of the stressed-skin type, that is, a. .construction wherein a metal skin itself together which is eflective to with load transfer 7 distribution of stresses at adjacent panel members members.

Patented Jan. 15, 1946 r OFFICE I 2,393,081 JOINT CONSTRUCTION Edward G. Philadelphia, Pa., 9. vania Application June 28,

23 Claims.

This invention relates to Joint constructions, particularly to an improved joint fo connecting a cantileverpanel to supporting structure or conendwise adjacent parts of a cantilever panel. such as, for example, an aircraft wing or other airfoil. 4

Inaircraft structures, for example, it is very manufacturing, shipping and repair purposes to make various parts in judicious subassemblies. This is particularly true in the case such as wings, it being the practice in many cases to construct the wing of two Outer panel and an inner paneL with suitable reinforcing elements, carries a considerable portion of the load, a portion of the joint connection is made through each skin-andreinforcement assembly to the adjacent wing or fuselage assembly. The skin and reinforcement assemblyis often called the'skin cover and sometimes the skin blanket. In Such a construction it is desirable to distribute the transfer of the shear stresses and axial loads incident to cantilever loading,-throughout a wide :region at the root ends of the skin blankets but substantially in the planes or the blankets.

The primary aim of the present invention is the provision of a newand improved Joint which is especially adaptable to cantilever loading, par: ticularly over an extensive region.

Another object is to provide a load transfer joint of improved construction for cantilever panel members of the stressedmetal skin type efllciently distribute stresses at the rootend thereof.

- Another object is to provide a panel member meansat one end thereof for a plurality of regions and which embodies in addition means fo trans ierring these stresses through improved shear connections to an adjacent member.

Another'objectis to provide a joint between wherein a plurality of connections canbe easily and quickly made and which in coniunction with closed panel members can be efilclently made from outside the panel- A furthe object is to provide a rigid-Joint of overlapping members in which the same is disposed along converging linesand the coupling members thereof are' arranged stepwise or in echelon with access spaces therebetween.

constructed that the tension and The Joint is so compression loads are transferred through the 1943, Serial No. 492,493 (Cl. '24'4 124) joint by shear in connecting bolts and the shear loads at the Joint are taken by the coupling elements and the skin gap covers which are provided.

The advantages of the and ease of assembly, ease of inspection, and greater structural efliciency.

' With the above and other objects in view which will be obvious to those skilled in the art, the present invention consists in certain features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawings, and then claimed.

The joint construction is shown, for the purpose of illustration, in connection with an aircraft wing 01' the type which includes skin covers or blankets embodying metallic skins and spanwise extending skin reinforcing-stringers, the wing embodying an outer panel and an inner panel, each panel comprising a leading or nose section, a center or main section, and a trailing. section, and the skin blankets being designed to carry the prin-' cipal stresses near the front and rear edges of the center section and with much less stress carrying capacity at the middle of the center section. The nose section construction also provides considerable stress carrying capacity, while the trailing' section'is required and designed to carry very little stress.

Gil

oi the center section and immediately in front of the trailing section. a

The coupling members are designed for convenient anchorage or rooting with the skin stringers and for easy registry with each other when the wing panels are brought together. They provide holes for chordwise disposed connecting 9 bolts which are stressed in shearphence are very secure, very strong for their size, more'reliable 40 against fatigue and excessive bolt tightening, and do .not warp the associated structure when tightened. I

An embodiment in the accompanying drawings, wherein: 1

Fig. 1 is a plan view-of the center and outer panels of'an aircraft wing assembly embodying the invention; I

Fig. 2 is an enlarged vertical chordwise section taken on the line 2-1 of Fig. 1; 60 Fig. 3 is an enlarged vertical chordwise section takenon the line 3-3 oi Fig. 1, the section being .the same as section 2-2 but the view being taken in the opposite direction and inverted; Fig. 4 is an enlarged top plan view taken about as in the rectangular area 4 of Fig.

joint include accessibility A stronger connection is made 30 through the rear spar which is located at the rear of the invention is illustrated I lwith the skin .and looking upward blanket;

section taken on the underside perspective being taken about in the line 2H 1'18. 22;

Fig. 5 is a view similar to Fig. 4 but showing the wing panels in the pre-assembly position and with less detail;

Fig.- 6 is a view similar to Fig. 4 but taken below Fig. "l is a partial enlarged vertical chordwise section taken on the line 1-1 of Fig. 4;

Fig. 8 is a partial section taken on the line 8-8 of Fig. 4;

Fig. 9 is a partial enlarged vertical chordwise section taken on the line '9-3 of 1;

Fig. 10'is a partial enlarged vertical chordwise section taken on the line Ill-Ill of 4;

Fig. 11 is a partial enlarged vertical s'panwise section taken on the line ll-H of Figs. 4 and 1 Fig. 12 is a partial enlarged vertical spanwise line li -l2 of Figs.4 and 10;

Fig. 13 is a partial section taken on the line 13- of Figs. 4 and 10;

Fig. 14 is a partial enlarged vertical spanwise section taken on the line l4--l.4 of Fig. 4;

Fig. 15 is a partial enlarged vertical spanwise section taken on the line Ii-N of Fig.

Fig. 16 is a partial tion of parts shown in plane of the view being indicated; by the line lS-IB inFigs. 12 and 13;

Fig. 1'7 is an enlarged end and topside perspective view of a portion of the outer wing panel, the view being taken about the line lI-ll enlarged horizontal secof Fig. 5;

Fig. 18'is an enlarged vertical section and view of a portion of the outer wing panel, the view being taken about on the line l8-l8 of Fi 5 and the section location being indicated also on Figs. 11, 12 and 13;

Fig. 19 is a side perspective view of the reinforing meansfor a Y-bulb blanket stringer element, the view being indicated by the directive lead lines IS in Fig. 18;

Fig. 20 is a side perspective view of the reinforcing means for the channel blanket strin er elements, the view being indicated by either of the directive'lead lines 24 inFig. 18; 1 Fig. 21 is a side. perspective view of the reinforcing m'cans for an end-slitted Y-bulb blanket stringer element, the 'view being directive lead line 2! in Fig. 18;

Fig. 22 is a partial leading or nose section oi! the wins. the view the area 22 ot F18. 4; Fig. 23 is a vertical chordwise section on the line 23-23 of Fig. 22;

Fig. 24 is a vertical chordwise section taken indicated by the taken on the line 24-24 of Fig. 22, the section bein the same as for Fig. 23 but the view being takenin the opposite direction and inverted:

Fig. 25 is a vertical spanwise section taken- .on the line 25-28 oi Fig. 22:

Fig. 26 is a vertical spanwise section taken Fig. 2'lis a vertical spanwise detail, the view beingataken 0!! the 11118 11- 21 Fig. 28 is a vertical ehordwi'se section of a small" g:tail2,2the view being takenon the was 28-20 of s- 7 1 Fig. 29 is a enlarsed'plan view of the toward the upper skin enlarged vertical, spanwise the area it "of Fig. 6, the.

enlarged plan view of the V at... oia small closure sheet removed and with certain parts shownin dotted lines;

enlarged vertical chordwise I The connections along each 0! planes are made through overlapping spanwise webs arranged stepwise or in hole is clear of adjacent joint couples at chordwise spaced locations trailing wing section. eview-jbei'ng taken about 7 in the area as ofFl8.1i

Fig. 30 is an enlargedvertical spanwise' section taken on the line H! oi 29;

' is located inboard horizontal bending outeawing panel.

selected which match in integral Fig. 31 is a partial enlarged verticalspanwise section taken on .4 and 29;

shown in Fig. 31;

Fig. 33 is a vertical chordwise section taken on the line 33-33 of Fig. 31;

Fig. 34 is a vertical chordwise section taken on the line 34-34 of Fig. 31; and

Fig. 35 (on Sheet '7 with Figs. 17-21) is a partial vertical chordwise section of a slightly modifled connective construction.

Gasman. Ammonium The present invention provides a strong joint between adjacent wing panels and is particularly applicable for connecting the outer wing. panel with the center wing panel, sometimes the inner wing panel because it however, the invention is equally adaptable to the connection or a single wing panel with an adjacent fuselage section. or to other constructions wherein the load 4 nsier by shear elements is involved. Such a joint is subjected to shearing stresses as well as tension and compression stresses because of the lateral forces imposed by the air upon the outer panel. The tionally imposes rotative torsional stresses in the joint. The joint provided hereby is well adapted to take the tension and compression stresses by reason of the fact that the connection is made between mating parts by bolts which are placed in shear rather than in tension sequentiy the stresses do not tend'to strip the threads on the bolts. The wing panels are pro!- erably joined on converging vertical planes. in 1 effect a truncated V-shaped joint, rather than on a single straight vertical chordwise plane and this provides a strong spanwise cantilever reaction in the joint. However, the panels may be joined along a single transverse vertical plane. the convergin extending shear echelon whereby each bolt hole is madev accessible from the side along a line which is laterally spaced spanwise from the line or acoessror each adjacent hole. Before the wing panels are brought together the line of approach {or each the end or the next lower shear left between the shear the bolts 0! the joint.

for placing and particular wins eonstru The connection for the tion illustrated herein is madeespecially with a corresp ndinsly light intermediate construction. thus accommodating countered and furnishing good resistance tothe due to forward night.

stresses Joint or coupling members are center Tbe out'er iointor' the broken line "-3! of Figs.

of the .outer wing panel;

and this addiand where conwebs oi. and this provides access the heavytorsional stresses en ment. Fig. 8 shows aaaaos' i with an additional stiifening member ll. .A nose coupling members, which must match theinner I once. in 'consequencedo not match in integral units with the outer wing panel stringers. However, they do match in half units, specifically there being a3 to 2 width relationship between stringers of the two panels. and their anchorage is correspondingly accommodated. This gives rise to several similar though specii-lcally different' anchorage'or root constructions which will be particularly described. It is to be understood,

however, that the stringers ofthe two panels may be of the same character, if desired.

The. wing panels include a heavy trailing or rear spar, and the joint provides a good connection for the adiacent'ends of this spar. Atthe portion of the wing under consideration the nose and forward portions of the wing serve as a front spar, and the joint provides a good connection for the adjacent ends of this spar-like construction. Behind the rear spar in the trailing section it is only necessary to provide a connective closure between the adjacent fabric-covered parts.

Gannon. ARRANGEMENT sr REFERENCE 'rq rm:

, Daawmcs The general arrangement is shown by Figs. 1

skin sheet]. is secured upon the nose plates 4! of the center panel A and asheet lhiponthe nose plates of the outer panel B. 1

Center section rib elements The rib L in the center section of the center.

panel (Fig. 2) comprises chords 50 and webs ll with vertical stiffening struts 52. Upon the chords 50 there are secured skin blankets 54 which include the skin sheets proper 55 and the skin stiffening stringers 56 and 51. The stringers B8 are located adjacent the leading and trailing edges of the skin blankets where the stresses are great, hence are of relatively heavy construction:

whereas the stringers 51 are located in the center of the blankets where the stresses are relatively small hence are of lighter construction. This particular stringer arrangement is disclosed in detail in another application. Marginal stringers 53 of flanged channel or hat-shape are provided immediately adjacent and parallel with the edges to-3. The center section connection, where the major stresses are carried and where some of the main advantages of the invention are realized,.is shown in Figs. 4' to 21, with a slight modification in Fig. 35. The leading or nose section connection is shown in Figs. 22 to 28. And the trailingsec tion connection is shownin Figs, to- 34.

Referring to Fig. 1, the wing W here illustrated,

in spanwise direction, comprises a'center or. inner wing panel A and an outer wing panel B, between which panels a joint C is established. It is this.

Joint with which the present invention is concorned. Inchordwise .direction the wing comprises a leadingor nose section D, a. center orof the blanket skin sheet. I 4

Similarly the ribsM in the center section of the outer wing panel (Fig. 3) comprises chords 80 and webs. 6| withstifiening struts Bland flanged stiffening apertures 63. Upon the chords 60 there are secured skin blankets 64 which-include the skin sheets prope'r 65 and skin stiffening stringers B6. The stringers 66 of the outer wing panel are much smaller than the stringers- 56 of the center @ving panel andare not, subject. I

to such greatly varying stresses as are thc'stringers of the center wing panel, hence, as shown, the stringers 68 may be of uniform size from the leading edge to the trailing edge of the. center main load bearing section E, and an aft or trailing section F. The center panel carries a motor nacelle G; and the'outer panel carries a tip H and an aileron (nohshown) which is supported by hinge brackets K mounted on ribs (not shown). Both the center. panel A and the outer panel B are provided with a number of chordwise extend-.- ing ribs but only two are shown herein, these being illustrated in side elevation in Figs. 2 and 3 and referred to generally as the center panel rib L of Fig. 2 and the outer panel rib M of Fig. 3. It is to be noted that the rib M of Fig. 3 is shown in inverted position. It is also to .be noted by reference to Figs. 6 and 23 that the nose rib here shown is not continuous with the center section 'ribelement but is similar to the next nose rib which is connected to the center section rib elereference is made to the ribs.

Nose section rib elements The nose elements of ribsL and M (Figs. 2-3

and also Figs. 23 and 24) comprise contoured.

flanged nose plates 40 and 4| respectively rein-. forced by generally vertical struts 42 and by integral pressed ridges or wales 43. The rib plate 4| adjacent one side (Fig. 24) may be provided section. in Fig. 3 there is an apparent difference between the stringers shown in the center from those shown at the edges but this'is caused by the joint construction as will be explained w hereinafter. Marginal stringers 59 of flanged channel or hat-shape are provided immediately adjacent and parallel with the edges of the blanket skin sheet.

Trailing section rib elements The rib elements of the trailing section of the centerwing panel (Fig. 2) comprise chords 10 and a connecting trusswork which includes the vertical struts l2 and the inclined struts l3. v The skin sheets 15 here may be of canvas.

Similarly the rib elements of the trailing section of the outer .wing panel (Fig. 3) comprise chords B0 and aconnecting truss-work which includes the vertical struts 82 and one or more in-. clined struts 83. The skin sheets 85 here may be of canvas.

Spanwise spar elements At the rear or trailing edge of the center sections of the center and outer wing panels (Figs. 1 to 3), where the greatest shear, torsional, and bending stresses are concentrated, there is provided a heavy rear spar which includes cap strips 92 and the web 94. The spar is connected across the joint C; as will be explained.

At the front Orleading edge of the center sec tio'ns of the center and outer wing panels respectively, but specifically included in the rear structure of the nose sections, top and bottom (Fig. 1), there are provided strengthening beam-like stringers lllll, iili whose ends are slightly oflset at the joint C, and means are provided for connecting these heavy stringers at the joint, The

oifset relation can be well seen in Fig. 6 and will be explained.

Csnrm Sscrron Jomr-Fms. 4 To 21 Referring to Figs. 4, 5 and 6, it can be seen that the truncated V joint comprises two converging lines of'step-wise-cr echelon arranged bolt connections, each joint or connection including a pair of overlapping coupling plates or flanges I05 and connecting bolts I06. As best seen in Fig. 5, the center lines of the bolt holes are spaced apart laterally (i. e. spanwise of the wing) by a considerable distance and stand clear of the end of the next adjacent lower plate I05. This provides clear access for drilling and reamiing, permits ready insertion of the bolts when the parts are assembled, and together withthe open spaces on each side, provides ample access .for holding the bolts and tightening the nuts thereon.

Joint coupling members Also, as well shown in Fig. 5, the plates I05 on each side are paired so as to fit in alternate pockets of the opposite side. The parts are almost symmetrical on opposite (front and rear) bers I I there is disposed a similar but shorterchannel member H and this includes side flanges H5 and a connecting web- III. The

flanges I05 and H5 of adjacent coupling members III, H 5 are welded together, as shown in Fig. 1'7, and within the ends of the projecting flanges I05 there are welded strengthening plates Ill. These plates IIO are provided with bolt holes which are aligned with those of the flange plates I05. The webs IIO, IIl'are cut away from the ends between the side flanges to provide access to the connecting bolts.

Typical members H0 and II! have been decribed. Some of the and members in each group depart from the typical. As shown in Fig. 5, on either. side of the intervening clear space where there are no connecting members at all, there are provided half members IIIla and H511 with flanges I05 and H5 and webs II In and II'Iin-respectively, corresponding to similar parts of the typical connection or coupling members.

On the leading edge of the center section of the center panel (Figs. 5 and 6) there is provided a narrow double-flanged member IIOb having flanges I05 and H5 and a web IIIb. There is also provided a mating half member IIOcto be.

welded to the flange I I0 of the member IIOb (see also the left side of Fig. 8) through the vertical web of the heavy front stringer member I00 of the center wing panel. On the leading edge of ing Z-shaped strut I20 is secured to the front side and over the outer end of the flange WM and intervenes between that flange and the companion flange I050 when the parts are assembled. This Z-shaped strut can be clearly seen in elevation in Fig. 26. One of its lateral flanges is welded to the web SI of rib L and the ends of the flanges are welded to the nose plate ll, Fig. '10.

- There is not much departure from the typical construction at the trailing edge so this will be taken up later.

Skin blanket stringers It will be helpful to observe the character of the skin blanket stiffening stringers because certain of them are involved in the rooting or anchorage of the connection or joint coupling membersIIOandII5.

As shown in Figs. 22, 23 and 24, the inner and outer nose skin sheets 46 and 41 are provided with several upper and lower spanwise' extending channel-shaped stiffening stringers I22 and I23 respectively.

The stiffening channel stringers 51 for the central portion of the center section of the center wing panel (see right side of Fig. 6), which'have heretofore been referred to, are hat-shaped in cross section and are welded to the skin sheets 55 through their flanges. In Fig. 6 the ends of the stringers are cut oil on a miter to indicate their cross-sectional shape. These center stringers are not utilized in coupling the wing panels together so do not require further consideration. However, it is to be understood that the invention is not limited to constructions embodying such stringers butthat all of the stringers may be of the type now to be described.

The stiflening channel stringers 56 of the front and rear portions of the center section of the center wing panel (Fig. 6) are uniformly of Y -bulb shape except the extreme front and rear ones 50 which are hat-shaped in section as heretofore described. The front one is clearly shown at the left side of Figs. '7 and 8.

As previously noted and as shown at the left of Fig. .6, the stringer members of the outer wing panel are all alike except those 59 at the extreme front and rear edges, as heretofore described.

and consist of alternating hat-shaped channel elements 561: and Y-bulb elements 66b. 'ihe bulb is in this case welded through inwardly extend ing edges to the outwardly extending edges of the adjacent channel stringers; but they are in effect Y-bulb stringers. Taking the distance between bulb stringers for comparison, the spacingof'bulb stringers .56 of the center wing panel is half again as great as that of the bulb stringer 56b of the outer wing panel, that is, there .is a 3 to 2 relationship in bulb stringer spacing. Consequently, as shown in Fig. 8, while the channelshaped connection or coupling members H0 and H5 match unit-for-u'nit with the stringers 56 of the inner wing panel, the companion coupling the center section of the outer paneliFigs. 5

and-6) there is provided a double flanged member IIld having a web Id and short inner flange H5, and having a long bent outer flange I054 adapted to be' bolted at its outer end to the protruding end of the companion flange I05c. A double thickness: strengthening plate II is secured to the flange I05d. A vertically extendmembers I I0 and H5 (Fig. 10) are one and onehalf times as wide as the spacing between bulbs 50b of the outer wing panel.

Root connection of joint coupling members The stringers areopened up back from their ends to receive the side flanges I05, 6 of the coupling members H0, H5. On the center wing panel (Fig. 8) it is only necessaryto separate the verticalwebs 50a of the stringers 55 and insert the 7s flanges I05, IIO of the coupling members, the

. stringer.

asaaoer stringers being deep enough to take-the full width,

of the flanges without cutting through the bulbs 581). On the outer wing panel (Fig. itisnecessary to slit the stringers because the flanges IIII, IIS of the coupling members are deeper than the stringers. The spacing of these stringers is such that it is necessary to slit Y-bulb stringers "b and channel stringers 66a in alternation, every third stringer of each type being slit. As shown in Fig. 16, the flanges I05, 6 of the ends of the center and outer win panels are suit-q ably made, as by welding as indicated, before the panels are connected together. The parts are held in Jigs during welding.

Blanket attaching clips Asshown in Figs. '1, 11, 12, and'13, the skin blankets are connected through their stringers coupling members H0, 'I I5 are tapered on their ends to feather out between the spread sides of the stringers. As shorwn in Figsvll, 12 and 13,- the webs I I I I II of the coupling members I I I), I is are also tapered at their ends to feather out toward the skin sheets. The non-typical end cou- I center wing panel, being deep as explained, are

merely spread apart at their ends to receive the side flanges I05, IIB of the coupling members. As shown at the left side of Figs. 12 and 13, the upp r flanges I25 of the Y-bulb stringers 56 are offset downward on the taper to receive the tapered ends of the web III, II I. Where necessary, as shown at the left of Fig. 8, the flanges I25 of the stringers 56 may be cut back and replaced by splice members I25a of diiferent size or shape.

The root construction for the coupling members I III, I It on the outer wing panel assumes two different specific forms, one fo the channel stringers 68a (Figs. 10,13, 18 and 19), and one forthe V-bulb stringers 66b (Figs. 10, 11, 12, 18, 20 and 21). Referring to Figs. 10, 13, 18 and 19, the channel stringers 86a are slit down the middle from one end to receive the flanges I05 and I I8 and are reinforced on each side by closely fitting flange strengthening members I27. A pair of these sheets are longer than the inner -portions.-

Referring toFigs. 10, 11, 12, 18, 20 and 21, the

\ Y-buib stringers 65b are slit down the middle from one end to receive the flanges I05 and H6 and are reinforced on each sideby closely fitting to the Z-shaped chords 5|) of the ribs L of th center wing panel by inte'rfltting clips I30. The clips here shownhave duplex heads 'I30a, I'3llb (Fig. 7) which are welded together through their main webs and welded to thesides of adjacent stringers 56 through their side flanges. The part ISIIa (Figs. 11-13) carries the bottom portion. I30c which is welded to the web and upturned flange of the rib chord 50.

In the center of the center panel (Figs. 4 and 14) the lighter and simpler clips 'I3I are used.

Their shape and-mode of connection is obviousfrom these views.

As shown in Figs. 9, 11, 12, 13 and 14, the typical clips I33 for the outer panel are provided only for the Y-bulb stringers 66b and are suitably shaped to flt the side thereof. Theyare welded through lateral flanges I33a at the topto the webs above the bulb and at thebottoms are welded 'to the webs of the Z-shaped rib chords 60 of the ribs M. Where the clips are secured over the stringer reinforcement elements they are suitably shaped to fit. I

In Fig. 10 there are shown several clips which depart slightly from the-typical to adapt them to the parts with which they fit. A pair of sim ilar clips I35 are secured to the reinforcing members I27 for the slit channel stringers. Another similar clip I36 is provided adjacent the dei'ormed strengtheningmembers I2! is shown in Fig. 19.

bers I 21 are considerably longer than the root connections; and, as shown in Figs. 13 and 19, the

flanged strengthening members I28. One of these a strengthening members is shown in Fig. 20, the -.-other being similar for the other side of the v The members I28 are wide enough and suitably shaped to cover the nextad- Y-blllb Stringer.

iacent channel stringer 66a and flt against the side of the next adjacent Y-bulb stringer 6%. In the left middle portion of Fig. 16 the extent of one of the strengthening members I28 can bev observed. 7

As shown in Figs. 10, 12, 18 and 21, where a bulb ofW-buib stringer 66b is slit there is provided,

in addition to the side reinforcing members I 28, a bottom reinforcing channel-shaped clip I 29. At

end ,Sfla of the heavy edge channel stringer 59. Also, as shown in Fig. 10 and by reference to Fig. 24, a clip I31 is welded to the rib chord BI! through its main flange and to the inside of the channel coupling member I Iild through bent flanges at its end, the heavy stringer member IIII and itsextension I Illa having terminated beyond the location of the clip I37.

. Joint closure strips Referring to Figs. 1, 11 to 15, 22 to 24, and 26, the top and bottom gaps in the skin blankets at the center section joint are closed after the connection has been made by finish or closure strips I38 secured by screws I39. In Fig. 4 the outline shape of thes strips and sockets for the screws are indicated. These strips are capable of taking the skin shear in these regions.

As shown in Figs. 4 to 6, the skin sheets 48, M.

of the nose sections AD and 3-D do not meet when the wing'panels are connected. The sheets welded to these projections 46a and 41a and, as

the outer end the clip I29 is deep enough to embrace the lower edges of the flanges IN, I Id of the coupling members II II, H5, and beyond the root ends of these flanges the clips I29 are tapered outward to flt the bulb. portion of the All root connections and reinforcements where shown in Fig. 25,these plates 46b, 41b are formed with mating inturned flanges I40 which are connected by bolts MI. A bent finish strip I42, secured by screws I43, closes the nose access opening after the connection has been made. Figs. 27 and 28 show how the screws are threaded into flanged screw bushings I 44 which are welded in the coupling members H0, H5 are grafted to the position.

" cation;

' the bolts I50 passes through each end of on of these angle members il. As shown in Fig. 31, the separate portions of the spar 80 are connected at the joint by bolts I52 which pass .through the rearwardly extending flanges of the angle mem bers l5l. As shown in Fig. 34, one of the coupling bolts I08 which passes through a coupling flange plate 105 also passes through the elements of the spar at each edge to make the spar stronger at the joint.

As shown in Fig, 33, the rear section chords" are provided withgussets I55 which are each secured to the spar 90 by one of the bolts I50, just noted, and by an additional bolt I58. Turning to Fig. 34. the chords 80 of the rear section are provided with gussets I 51 which are each secured to the spar'90 by bolts I58.

Referring to Figs, 29 and 30, the space on each side of the Joint in the trailing section is covered by plates I60 and Iii, on the center and outer panel sides respectively, and these plates are strengthened by chordwise stringers I 62, and by spanwise sub-stringers m. The sub-stringers I are secured at their ends to angle brackets I65 fast on the rib chords II or 80.

There is practically no strain to be taken across the joint in the trailing section, hence there is no need for heavily connecting the parts across the joint here. The space between the plate I60 and lBl'is covered by rear finish strips I61 and these strips may be retained by snap clips I68 or by screws I69, or both, as desired. Access openings in the front ends of the plates I60, lfil'are closed by caps I10 which are secured by screws I'll.

Monrrmn OonnLmc-Frc. 18

m Fig. 18 (Sheet 7 of-the drawings) there is shown a slightly modified coupling construction in which the holes in the shear webs I05 of the U-shaped coupling members llil are provided It-is' thus seen that the invention provides an improved joint which utilizes shear members adjacent each surface to be joined andthat the Joint is so shaped'and its elements so arranged a,sos,oe1 Y willbe understood that the invention may have and transfer" structure including a plurality of parallel channel members secured to the blanket with their axes directed toward the end thereof. the side flanges of the channel members of each blanket engaging and being rigidly secured to the side flanges of adjacent channel members, and alternate channel members of each blanket projecting axially beyond the intermediate channel members .to provide recesses therebetween, the projecting channel members of each blanket extending intb the recesses formed between the projecting channel members of the end-adiacent blanket and having their side flanges engaging the side flanges of the channel members of the end-adjacent blanket, and shear bolts extending through the inter-engaging side flanges of the projecting channel members of end-adjacent blankets. v

2. In a jointed cantilever panel construction which includes a pair-01' endwise adjacent panels of the stressed skin type, each panel including laterally spaced skin blankets secured on oppo site sides of a frame, the combination therewith of means providing a connection between the blanket of one panel and the end-adjacent blanket of the other panel on each side ofthe frame, said connecting %means comprising for each of the blankets a rigid load distribution and transfer structure including a plurality of parallel channel members secured to the blanket with as to provide maximum strength and accessi -bility with minimum weight and possibility of failure. The invention has been described in connection with a wing and a wing of certain characteristics but it has more general appli- While one embodiment of the invention has been described for purposes of illustration it their axes directed towardthe end thereof, the side flanges of the channel members of each blanket engaging and being rigidly secured to the'side flanges of adjacent channel members, and alternate channel members of each blanket projecting axially beyond the intermediate channel members to provide recesses therebetween, the projecting channel members of each blanket extending into the recess formed between the projecting, channel members of the end-adiacent blanket and having their side flanges engaging the side flange; of the channel members of the end-adjacent blanket, and shear bolts extending through the inter-engaging side flanges oi the projecting channel members of end-adjacent blankets, the channel members projecting beyond the skin blanket at each Joint zone and having the webs between the side flanges oi the channel members cut away to permit access to said shear bolts from the outside of the panels.

3. A Joint construction for a pair of adjacent structures, one of which is a cantilever panel having laterally spaced skin blankets secured to opposite sides of a frame, each blanket embodying a sheet metal skin and a plurality of longitudinally extending stringers thereon with their axes directed toward the joint end of the blanket. a transrersely rigid Joint structure for each blanket extending transversely of and rigidly secured to the ends of the strinzers and to-the end .of the skin, each said Joint structure comecade-1f prising a plurality of spaced stringer-wise tending flange portions projecting laterally irom one side oi. the skin toward. the opposite skin ior side-overlapping am sement with corresponding flange portions of the other of said adjacent members, each pairof overlapping flan e portions having a bolt opening extending th'erethrough transversely of the axes of the stringers and approximately parallel to the skin sheet, and a shear bolt passing through the holes of each pair of overlapping flange portions.

4. A joint construction for connecting endadiacent panels together, each panel embodying a sheet metal skin and a plurality of longttudinally extehding stringers secured thereto with their axes directed toward the joint end of the panel. comprising for each panel a plurality oi laterally spaced stringer-wise ex'tendingplatelike elements disposed approximately perpendicular to the panel skin, having their inner ends rooted to the ends or said stringers, and having their outer ends projecting to overlap and be connected by shear elements to similar platelike elements of an adjacent panel. the perpendicular plate-like elements of each panel being provided with angularly extending plate-like elements parallel with and secured to the panel skin.

5. A joint construction for connecting endadiacent panels together, each panel embodying a sheet metal skin and a plurality of longitudinally extending stringers secured thereto with their axes directed toward the joint end the panel, comprising for }each panel a plurality of laterally spaced stringer-wise extending platelike elements disposedapproximately perpendicular to the panel skin, having their inner ends rooted to the ends of said stringers, and halving their outer ends projecting to overlap and be connected by shear elements to similar platelike elements 01 an adjacentpanel, said platelike elements being provided with lateral webv elements which are also rooted at their inner ends to said stringers, said webs having parts of their outer ends cut away to provide access therethrough to the outer ends of said platelike elements.

6. Ajoint construction for connecting longitudinally aligned inner and outer end-adjacent els together, comprising in combination, a plurality of laterally spaced longitudinally extending plate-like elements anchored to the ad- .jacent ends of the panels and disposed approximately perpendicular to the plane of said panels. the plate like elements of opposite panels over-' lapping on the sides at their ends in pairs and being provided with aligned transverse holes the axes of which are approximately parallel to the plane 01' the panels, and shear bolts passing through said holes, the plate-like elements of each panel being secured tobacking web means which is eflectively continuous as a rigid element along the end of the panels to connect a pluralit oi plate-like elements, and said backing 7 web means iorminga panel-reinforcing shear taking element of the connected panel structure.

7. A joint construction for connecting longitudinally aligned end-adjacent inner and outer panels together, comprising in combination,lon-

gitudinally extending plate-like elements anchored to the ends of adjacent panels and disposed approximately perpendicular to the plane of the panels, the plate-like elements of opposite panels overlapping on the sides at their ends in pairs and being provided with mating transverseholestheanesolwhichare .paralleltothepiane-oithepanela bolts passingthroulhsaidholes, the plate-like 'elements orcach panel being provided withinli terconnectingbackingweb meanssecuredtothe" panels and forming a lateral beam-like shear taking element or the connected panel structure, said backing web means being cut back at the ends between adjacent webs-to provide openings .10 for access to the shear bolts therebeneath. s

8. 'A panel joint construction, comprising in combination an inner panel, an end-adjacent outer panel aligned therewith,-a skin blanket on each side or each panel, said skin blankets each including a skin sheet and longitudinal stringers therefor with their axes extending toward the end or the panel. each stringer including a base portion secured to the skin sheetand an outstanding portion extending away irom and approximately normal to the skin sheet, and coupling means tor connecting the end-adjacent skin blankets at the same sides of said panels together, said coupling means including a plurality of mating pairs or plate-like elements which are approximately normal to the skin sheet t and which are connected by transversely extend-- ing shear means which are approximately parallel to the skin sheet, said plate-like elements being provided with backing webs parallel to the skin sheets, and said plate-like elements being anchored to said stringers in their outstanding portions.

9. A joint construction through which a may be anchored to an adjacent part, compris ing in combination, a' panel skin blanket including a skin sheet and stringers having their axes directed toward the end of the blanket, each stringer including a base portion secured to the skin, sheet and an open rib-like portion extend- 40 ing away from the skin sheet, and coupling means for connecting the skin blanket to an adjacent part, said coupling means including a stringer-wise extending U-shaped member having its side flanges and back anchored to said stringers. the side flanges being located in the rib-like portions of the stringers, and certain of said side flanges having transverse holes in their outer ends adapted to take a transverse shear bolt to anchor the panelto the adjacent part.

may be anchored to an adjacent part, comprising in combination, a panel skin blanket including a skin sheet and stringers having their axes directed toward the end oi theblanket, each stringer including a base portion secured to the skin sheet and an open rib-like portionextending away from the skin sheet, and coupling means for connecting the skin blanket to an adjacent part, said coupling means including a stringers wise extending U-shaped member having its side flanges and back anchored to said stringers, the side flanges being located in the rib-like portions of the stringers, and certain 01' said side adapted to take a transverse shear bolt to anchor the panel to the adjacent part, the stringer 11. A joint construction through which a panel may be anchored to an adjacent part, comprising in combination, a panel skin blanket including a Skin sheet and stringers having their axes 10. A joint construction through which a panel flanges having transverse holes in their outer ends-- directed toward the end of the blanket, each stringerincluding a base portion secured to the skin sheet and an open rib-like portion extending'away from the skin sheet, and coupling'means for connecting the skin blanket to an adjacent part, said coupling means including a stringerwiseextending U-shaped member having its side I of the stringers, and channel-shaped reinforcing members secured over the ends of the stringerswhere slitted.

12. A joint construction for connecting longitudinally aligned end-adjacent panels together, comprising in combination, a plurality of laterally spaced longitudinally extending plate-like elements anchored to the adjacent ends of the panels and disposed approximately perpendicular to the plane of the panels, the elements of opposite panels overlapping on the sides at their ends in pairs and being provided with aligned transverse holes, and shear bolts passing through the holes'of each pair, said joint including a plurality of such shear connections arranged along converging joint lines in the plane of and within a relatively short portion of the length of the panels. I

13. An airfoil joint construction, comprising in combination, an inner panel and an outer panel each including spaced skin sheets and each skin sheet being provided with a connecting joint formed by overlapping members anchored to the adjacent ends of the panels and disposed approximately perpendicular to the plane of the panels, the members of opposite end-adjacent panels overlapping on .the sides at their ends in pairs and being provided with aligned transverse holes, and shear bolts passing through holes of each aaeaosi the adjacent shear elements of a joint being located at diiferent points relative to the length of the" longitudinal axis of the panel.

1'7. An airfoil joint construction comprising in combination, an inner airfoil panel, an outer airfoil panel, and means for coupling said panels, said coupling means including mating pairs of longitudinally extending side-overlapping plates, one of each pair of plates being secured to each panel and said pairs being spaced apart'laterally,

said plates being provided with holes for connecting shear bolts which are arranged with their axes in trans-plate planes and inclined in the transplate plane relative to a perpendicular line through the plate and relative to the surface of the airfoil sufllciently to permit access to the bolt holes in the lines of their axes beyond the side edges of adjacent coupling plates after the panels are brought together.

18. An airfoil panel adapted to be connected in longitudinal end-adjacent relation to an adjacent structure, said panel including a skin sheet provided with a plurality of laterally spaced longitudinally disposed joint plates which stand approximately perpendicular to 'the skin sheet, said plates each being provided with a transverse shear bolt hole, and the bolt holes of adjacent plates being disposed in echelon to permit access on one side of the plate in the line of a hole beyond the end of the adjacent plate on that side.

19. An airfoil joint construction, comprising in combination, an inner panel and an end adjacent outer panel each including a nose section, a center section, and a trailing section, joint means for connecting said center sections along converging lines in the plane of and within a relatively short portion of the length of the panel, and means for connecting the nose and trailing sections along transverse lines which run outward from the more distant ends of the converging joint lines of the center panel sections.

20. A panel joint as for an aircraft airfoil panel,-

' comprising in combination, a. panel including a pair, said joint including a plurality of such shear connections arranged along converging lines in the planeof and within a relatively short-portion of the length of the panels.

14. An airfoil joint construction, comprising in combination, an inner panel and an outer panel provided with a connecting joint therebetween formed by side-overlapping plate members connected by shear elements, said joint including a plurality of shear elements arranged along converging lines in the plane of and within a relatively short portion of the length of the panels.

15. An airfoil joint construction, comprising in combination, aninner panel and an outer. panel provided with a connecting joint therebetween formed by side-overlapping plate members connected by shear elements, said joint including a plurality of shear elements arranged along converging lines in the plane of the panels, said shear elements being arranged along converging lines which form the sides of a trimcated v.

16. An airfoiijoint construction, comprisingin combination, an inner panel and-an end-adjacent outer panel each including laterally spaced ;skin sheets and each pair of'end adjacent skin sheets being provided with a transverse connecting joint formed by a plurality of pairs of longitudinally extending side-overlapping plate members connected by transverse shear elements,

skin sheet and stringers secured to the skin sheet. with their axes directed toward the end of the sheet which is connected to an adjacent structure, said stringers including base portions secured to the skin sheet and adjacent parallel side wall portions which extend away from the skin sheet in an approximately perpendicular direction; plate-like joint elements disposed between the adjacent parallel side wall portions of the stringers and secured thereto by shear means,

the plate-like elements thus also being approximately perpendicular to the skin sheet, mating parallel plate-like elements on the adjacent structure, and shear means connecting together the plate-like elements of the panel and the adjacent structure in side-overlapping disposition.

, 21. A panel joint as for an aircraft airfoil panel, comprising in combination, a panel including a skinshect and stringers secured to the skin sheet with their axes directed toward the end of the sheet which is connected to an adjacent structure, said stringers including base portions secured to the skin sheet and adjacent parallel side wall portions which extend away from the skin sheet in an approximately perpendicular direction, plate-like joint elements disposed between the adjacent parallel side wall portions of the stringers and'seeured thereto by shearmeans,

the plate-like elements thus also being approximeans connecting together the plate-like elements of the panel and the adjacent structure in sideoverlapping disposition, said plate-like Joint elements being provided adjacent each side of the panel but being omitted at the center of the panel.

23. A panel joint, as for an aircraft airfoil panel, comprising in combination, a panel including a skin sheet with stiff stringers secured therewhich extend away from the skin sheet in .an

approximately perpendicular direction, platelike joint elements disposed between the adjacent parallel side wall portions of the stringers and secured thereto by shear means, the plate-like elements thus also being approximately perpendicular to the skin sheet, mating parallel platelike elements on the adjacent structure, and shear 20 i to on one face in a zone at each edge thereof, and 7 joint means for connecting the panel to an adjacent structure, said joint means including a transverse beam-like structure secured across the end of the panel in each edge zone, and a plurality of shear coupling plates secured to each'beam-like structure, said plates being approximately perpendicular .to the skin sheet and secured to the stringers and skin sheet, andthe'central zone of the panel at the joint being left free of said shear coupling plates.

MICHAEL WA'I'IER. 

